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20

Unfortunately, we are all still "confuzzled" by how memory works. We are far from a complete understanding of how memory is stored and recalled. Nonetheless, we do know a little, so read on. Your understanding of basic neural function is almost correct. First, an individual neuron will signal through its single axon onto the dendrites of many downstream ...


12

You would need to live a long, long, long, long time for this to become remotely problematic. Your question seems to suppose that a memory is "stored" by a neuron, and since neurons have mass, then the more memories we have the more our brains will weigh. Actually, neurogenesis is pretty rare in the adult brain--most of the cortex is fixed, and new neurons ...


11

Its not clear that this is true. Working with animals has been a little disconcerting over the past 50-60 years. In the distant past, I think most evolutionary anthropologists and their like bought into the idea that humans were completely uniquely intelligent and spiritual. But the more we try to define human sensibilities apart from other animals, the ...


7

Well, Erickson et al (2011) attribute the increase in brain volume in the aerobic exercise group to brain-derived neurotrophic factor (BDNF). Specifically (p. 3020): In fact, we found here that changes in serum BDNF levels were associated with changes in anterior hippocampal volume; an important link because the hippocampus is rich in BDNF, and BDNF ...


7

The newest and most accurate method (far more accurate than older extrapolating/manual counting methods (Stereology) and yielding some surprising results) to estimate number/density of neurons/cells in brains is Isotropic Fractionator to my knowledge. Using this keyword you find some recent papers, comparing different brain areas (cerebral cortex, ...


6

Although tinnitus is usually described as a ringing in the ear, there's a whole range of tunes, buzzes, whooshing sounds, humming and hissing sounds that are described of as tinnitus. The sounds can either genuinely be there or be perceived to be there. If it is genuinely there it suggests muscles ate at play or some blood vessel disease if the sounds are in ...


5

I haven't read anything particularly about dendrites being reshaped, though I would expect them to be as flexible as other parts of the cells. The more commonly discussed topic (in my literary experience) is reshaping of the axon's branches before forming synaptic terminals. These branches are not fixed even in adults - neurons can grow new and retract old ...


5

I would like to point out some ways your understanding is wrong. "Neural networks" are usually a computer science term, only very, very loosely based on actual neural networks. The idea of layers in a neural network is pretty much an invention of computer science, it doesn't really reflect the reality. Also, neurons are not binary switches. It isn't so much ...


4

Microtubules are a structure in the cytoskeleton, they are rope like polymers that grow to a length of about 25 micrometers (25000 nm), and have an outer-diameter of around 25 nm. For comparison, the mean spacing between atoms is on the order of 0.1 to 0.2 nm; so the micro tubule really is micro: about 200 atoms across. In terms of quantum effects though, ...


4

Mechanical force can compress neurons and cause action potentials as you probably experienced in the form of hitting the funny bone. Strong enough acceleration of the brain tissue may be causing massive excitation of neurons as indicated by animal EEG study. It suggests that the loss of consciousness is due to generalized epileptic seizure. However, it is ...


3

Its pretty well established that there are photoreceptors in cells besides the cones and rods in the retina of the eye. Humans and most animals have four light receptor genes known (so far). In addition to Rhodopsin - there are the short, med and long wavelength opsin genes. While they are mostly expressed in the retina of the eye, they can be found in ...


3

One of the many advantage of an all-or-none system is that resources can be conserved for timing events that require synchronized collaboration between many cells (like locomotion). Binary behavior may also partially be a side effect of speed and efficient long-distance information transfer (which is one of the great advantages of neurons as cells in the ...


3

There are a number of different wiring scenarios that could lead to this type of behavior, even in a dissociated neuronal cell culture. The two major cases are neurons that are truly isolated from each other, and collections of neurons that connect together. Since your question refers to firing and synchronized bursts, I'll restrict my discussion to the ...


3

I've found a rough answer myself: The globe of the eye, or bulbus oculi, is the eyeball apart from its appendages http://en.wikipedia.org/wiki/Globe_%28human_eye%29 ... the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the ...


3

I think is closer to 2. It is the subset of sensory space that elicits a reaction in a given neural population. So you should: Pick your neural population. Usually it is a single neuron (but can be easily extrapolated to bigger populations). It may be a sensory neuron, or a neuron in a higher processing region. Determine your sensory space. That is, you ...


3

I would say no. You question somehow implies that somatosensory cortex is equally distributed among the different sensory areas of the body, whereas in the reality this is the known "cortical homunculus" concept of how this distribution looks: If you look at this representation you'll see that chest and legs take only about one third to one fourth of the ...


3

You are completely right with your guess that is was Ramón y Cajal who first described these cells in his famous monograph "Histologie de systeme nerveux de l'homme et des vertebres." published in Paris Maloine in 1911. Since the only method he had at his disposal was Golgi's staining which is a pure anatomical staining (there is no living cell left in the ...


2

As you've already mentioned, cells near the primate macula tend to make one to one connections. Due to this lack of convergence they can be somewhat smaller than normal cells (particularly in the size of their dendritic arbors) earning them the moniker "midget" ganglion and bipolar cells (also P cells). By reducing the magnitude of photoreceptor ...


2

The situations you describe involve what is called proprioception or the feedback to the brain of where your arms and limbs are in space. As APengioun mentioned, this is a complicated undertaking and if information is restricted, for example eyes are closed then the sense of where your limbs are gets messed up. As for your title, it's not really neuronal ...


2

When our brain works out where a part of our body is in relation to another part of our body, or in relation to anything for that matter, we combine: visual information information about how much our muscles are contracted how much our joints are contracted different forces being applied on our arms/legs or other body parts where it remembers we used to be ...


2

A LFP can be measured at any point in space and is just the sum of all the fields generated by nearby charges. Conventionally, it's assumed to be some distance from a cluster of neurons, but you technically could measure the LFP near the external surface of a neuron (but that would bias your signal towards the reading of that one neuron). LFP's are ...


1

+1 for giving a solid answer to @AP, but being older I've had friends who have had tinnitus and I'd like to add some notes to try to flesh this out a bit. I don't think tinnitus is the result of nerve damage usually. Nearly everybody experiences episodic tinnitus at one point or another. When exposed to a loud sound or a blow to the head can cause it. ...


1

What changes in the process of learning: The connections (the way one neuron is connected to another). New synapses can form or dissolve in the process of learning. The glial cells such as astrocytes and microglia can facilitate this process. Strength of connections: Existing connections can be made weaker or stronger in the process of triggering the same ...


1

In RBF networks each neuron in the hidden layer applies a computation that is related to its "center vector". First consider the set of input neurons as a vector $\mathbf{x}$, and that each hidden layer neuron receives the complete input vector as its own input. Second, each hidden layer neuron $i$ is parametrised through a vector (center vector) ...


1

Loss of consciousness, or syncope, can be caused by a number of factors, almost all of which relate to lack of proper blood flow: high G-forces, low blood pressure, low blood sugar, cardiac arrhythmia, and vasovagal responses, such as when I give blood. These all make sense and are moderately well understood. The mechanism of loss of consciousness due to ...


1

No, it is not 1. the structural distribution of the neurons themselves. If by mapping you mean a kind of function that maps real space to cognitive space (or such) then it is not that either (at least, not explicitly/directly). The receptive field is the region of 3D space in which sensory neurons can make their relevant detection. It's not a ...


1

We already remove old ones and create new ones. I doubt you remember most of Geometry, for instance. As for capacity, this article from Scientific American gives a good overview of what we can estimate with our current knowledge. For comparison, if your brain worked like a digital video recorder in a television, 2.5 petabytes would be enough to hold ...


1

The mechanism of action of cocaine is dependent on pre-existing dopamine production and secretion. Normally, secreted dopamine is cleared from the synapse via the dopamine transporter (DAT) located on presynaptic dopaminergic terminals. Cocaine inhibits this reuptake of dopamine, increasing it's duration of action on post-synaptic dopamine receptors. Thus, ...



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